» » Difference between float and double java

  • Float data type in java is represented in 32 bits, with 1 sign bit, 8 bits of exponent, and 23 bits of the mantissa
  • Where as Double is  is represented in 64 bits, with 1 sign bit, 11 bits of exponent, and 52 bits of mantissa.
  • Default value of float is 0.0f.
  • Default value of double is 0.0d.
  • Floating points numbers also known as real numbers and in java there are two types of floating point one is float and another one is double.



  • Float specifies single precision and double specifies double precision.
  • According to the IEEE standards, float is a 32 bit representation of a real number while double is a 64 bit representation
  • Normally we use double instead of float to avoid common overflow of range of numbers
  • Check below diagram for width and range of float and double data types


float vs double java


 When do you use float and when do you use double:

  • Use double data type for all your calculations and temp variables. 
  • Use float when you need to maintain an array of numbers - float[] array (if precision is sufficient), and you are dealing with over tens of thousands of float numbers.
  • Most of the math functions or operators convert/return double, and you don't want to cast the numbers back to float for any intermediate steps.

How many significant digits have floats and doubles in java?

  • In java float can handle about 7 decimal places.
  • And double can handle about 16 decimal places

Program #1: write a java example program which explains differences between float and double in java

  1. package com.instanceofjava.floatvsdouble;

  2. import java.math.BigDecimal;


  3. public class FloatVsDouble {

  4. /**
  5. * @website: www.instanceofjava.com
  6. * @category: float vs double in java with example program
  7. */
  8. public static void main(String[] args) {
  9.     float  a=10.8632667283322234f;
  10.     double b=10.8632667283322234f;
  11.     
  12.      System.out.println("float value="+a);
  13.      System.out.println("double value="+b);
  14.         
  15.      b=10.8632667283322234d;
  16.         
  17.     System.out.println("float value="+a);
  18.     System.out.println("double value="+b);
  19.        

  20. }

  21. }

Output:

  1. float value=10.863267
  2. double value=10.863266944885254
  3. float value=10.863267
  4. double value=10.863266728332224

Difference between float and double java

Instance Of Java

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